This invention relates to electrical connector feedthrough as used in electrical and electronic apparatus, and more particularly the invention relates to an electrical connector feedthrough to a low pressure chamber in such apparatus.
Mass spectrometers are well known scientific instruments for analyzing chemical structures. A mass spectrometer includes an ion source, an ion filter, and an ion detector positioned in a low pressure (e.g. vacuum) chamber. Gas at low pressure is introduced into the ion source which ionizes the gas. Ions are then selected by the ion filter and passed to the ion detector. The ion filter selects ions having a particular m/e ratio which may be varied to analyze the gas. Examples of mass spectrometers are described in U.S. Pat. Nos. 5,559,327; 5,389,785; 5,298,745; 4,949,047; 4,885,470; 4,158,771; and 3,757,115.
Electrical connection must be made to contacts within the vacuum chamber to transfer electrical power and electrical signals between components in the chamber such as quadrupoles and ion lenses and circuitry in the ambient atmosphere. To function properly the pressure inside the chamber must be below 10-7 Torr. Typically, multiple different types of electrical signals are required within the same assembly, such as high voltage, high current and shielded signal. More recently vacuum chambers are made out of single block aluminum for cleanliness, disallowing welding. These chambers are also heat cycled for cleanliness, making different thermo expansion become a problem. Traditionally, vacuum feed-through are ceramic-metal brazed pins mounted on metal flanges which in turn are mounted on to the analyzer chamber (U.S. Pat. Nos. 4,176,901/4,231,003), or wired into a flange (U.S. Pat. No. 6,093,886). An alternative to sealed pin technology for the fabrication of cable feedthrough devices entails the use of epoxy materials for the formation of vacuum-tight seals, as described in W. D. Wood and W. L. Wood, "Hermetic Sealing with Epoxy" in Mechanical Engineering, Mar. 1990, Pave Technology Co. This technology, however, is suitable only for devices exposed to temperatures down to about -65.degree. C. Heretofore, Kaplan boards imbedded in plastic have been employed as feedthroughs with a sealant provided on the outer surface of the chamber for pressure sealing the feedthrough. This arrangement is difficult to fabricate and assemble.
The present invention is directed to an improved feedthrough for a low pressure chamber which is easily assembled and replaced, yet effective in sealing the chamber. Further, the feedthrough can be best cycled and permits a common PCB type connector in the assembly.